Review of studies in high level natural radiation areas in India

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The necessity to investigate the HLNRA in Karunagappally in Kerala, India was emphasized by the WHO as early as 1959. BARC since 1960, started studies on the detrimental effects of HLNR on biological systems. Studies of Grunberg et al (1966) on rats and those of Gopal Aiyyengar (1972) on human were not suggestive of any positive genetic effect. Cytogenetic studies on Flora from these areas have indicated significant positive correlations between cytological damage, external radiation levels and internal radionuclide content in plants (George et al, 1991). Monitoring of newborns at birth for malformations and a comprehensive Health Audit Survey by the BARC team indicated that HNLR in Kerala has no heritable effect on humans (Thampi et al, 2004).
RCC, Trivandrum in 1990 initiated a baseline socio-demographic lifestyle survey, radiation level measurements (dosimetry) and Cancer Registry in this area. Analysis of 181 soil samples in this area indicated ²³²Th to be the main radiation contributing source. Radiation levels between and within the panchayaths showed large variations and a radiation cohort has been identified (RRK Nair et al, 2004). Since 1990, NBRR of RCC, has been studying the cancer causing potential of HLNR. At the end of ten years of study, NBRR was in a position to assert that there is no alarming increase in cancer due to HLNR (Gangadharan et al, 2004; jayalekshmi et al, 2004). RCC has already initiated studies to calculate the cumulative dose after measuring the individual exposure rate and to evaluate the cytogenetic effects of the same.